Vehicle having variable oil pump

ABSTRACT

A vehicle having a variable hydraulic pump may include a sun gear that receives a torque from a power source through an input shaft, a ring gear of which an interior circumference is with a distance from an exterior circumference of the sun gear, a planetary gear that is disposed between the interior circumference of the ring gear and the exterior circumference of the sun gear, a carrier that connects with an output shaft, a hydraulic pump that pumps oil through the output shaft that is connected to the carrier, and a motor that is disposed outside the ring gear to selectively rotate the ring gear.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority of Korean Patent Application Number 10-2013-0025571 filed Mar. 11, 2013, the entire contents of which application are incorporated herein for all purposes by this reference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a vehicle having a variable hydraulic pump that variably changes load of hydraulic pump for generating hydraulic pressure that is necessary for an engine or a transmission to reduce energy loss and cost.

2. Description of Related Art

Recently, fuel consumption saving art has been researched to reduce CO2, and an ISG (Idle stop and go) system turns off engine in a predetermined stop condition and restarts the engine in a predetermine restart condition.

The ISG (Idle Stop and Go) system uses information such as vehicle speed, engine rotation speed, coolant temperature, and so on to stop the engine in a predetermined condition and thereafter enables normal driving by restarting engine in a case that the restarting of the engine is demanded by a vehicle condition.

The ISG system stops an engine to enter into an idle stop condition when an engine is sufficiently warmed up, a coolant temperature is higher than a predetermined value, a condition that a vehicle speed is low or at zero (0), a shifting position of a transmission is neural, and a brake pedal is operated for a predetermined time.

The ISG device can increase fuel consumption efficiency of a vehicle up to 5 to 15%. Generally, an automatic transmission (AT) has to have a motorized hydraulic pump that supplied oil pressure thereto in an idle stop condition of a vehicle having ISG system.

Accordingly, the vehicle having an automatic transmission and an ISG system includes a mechanical pump that is disposed in the automatic transmission to be operated by an engine in the ISG none operation condition and generates hydraulic pressure necessary for controlling the automatic transmission and an auxiliary motorized hydraulic pump that is operated in the ISG operation condition to generate hydraulic pressure for the automatic transmission.

The vehicle having the automatic transmission and the ISG system has two pumps that are a mechanical pump and an auxiliary motorized hydraulic pump, wherein the mechanical pump is operated during the operation of the engine and the auxiliary motorized hydraulic pump is alternatively operated during the none-operation of the engine.

The vehicle having the automatic transmission and the ISG system has to have two pumps having equal functions, and therefore vehicle cost is increased, vehicle weight is also increased, and the fuel consumption is deteriorated.

The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY OF INVENTION

The present invention has been made in an effort to provide a vehicle having a variable hydraulic pump having advantages of minimizing energy lost by hydraulic pump, fuel consumption, and fluctuation of hydraulic pressure by optimally controlling the load of hydraulic pump.

A vehicle having a variable hydraulic pump according to various aspects of the present invention may include a sun gear that receives a torque from a power source through an input shaft, a ring gear of which an interior circumference is with a distance from an exterior circumference of the sun gear, a planetary gear that is disposed between the interior circumference of the ring gear and the exterior circumference of the sun gear, a carrier that connects with an output shaft, a hydraulic pump that pumps oil through the output shaft that is connected to the carrier, and a motor that is disposed outside the ring gear to selectively rotate the ring gear.

The vehicle having a variable hydraulic pump may further include a shaft one way clutch that has the input shaft rotate in one direction, and a ring gear one way clutch that has the ring gear rotate in the other direction. The power source may be an internal combustion engine or a motor.

The vehicle having a variable hydraulic pump may further include a controller that controls the motor depending on a rotation speed of the input shaft such that the hydraulic pump is controlled at a predetermined optimized speed. The motor may be operated at a predetermined rotation speed such that the pump is operated at a minimum rotation speed in an idle stop condition. A compensation value may be applied to a target rotation speed of the hydraulic pump depending on a temperature of the oil, when the power source is operated.

In a vehicle having a variable hydraulic pump according to various aspects of the present invention, the rotation speed of the hydraulic pump is optimally controlled by a motor in accordance with the rotation speed or driving conditions of an engine to be able to reduce lost energy. Also, the fluctuation of hydraulic pressure that is formed by the hydraulic pump is reduced to be able to improve the stability. Further, compensation value is applied in accordance with oil temperature to be able to safely generate hydraulic pressure and one motor is used to optimally control the load of the hydraulic pump.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of an exemplary variable hydraulic pump that is disposed in a vehicle according to the present invention.

FIG. 2 is a schematic diagram of an exemplary variable hydraulic pump that is disposed in a vehicle according to the present invention.

FIG. 3 is a schematic diagram showing an operational method of an exemplary variable hydraulic pump that is disposed in a vehicle according to the present invention.

FIG. 4 is a graph showing a compensation value that varies depending on oil temperature in an exemplary variable hydraulic pump according to the present invention.

FIG. 5 is a flowchart showing a control method of an exemplary variable hydraulic pump that is disposed in a vehicle according to the present invention.

FIGS. 6A, 6B, 6C and 6D are schematic diagrams showing operational conditions of a variable hydraulic pump of a vehicle according to the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

FIG. 1 is a schematic cross-sectional view of a variable hydraulic pump that is disposed in a vehicle, and FIG. 2 is a schematic diagram of a variable hydraulic pump that is disposed in a vehicle according to various embodiments of the present invention. Referring to FIG. 1 and FIG. 2, a variable hydraulic pump of a vehicle includes an engine 100 as a power source, an input shaft 160, a shaft one way clutch 155, a sun gear 110, a planetary gear 105, a ring gear 140, a ring gear one way clutch 150, a motor 145, a carrier 115, an output shaft 120, a hydraulic pump 135, and a pump housing 165. Further, the pump housing 165 includes a suction passage 125 through which oil is sucked to the hydraulic pump 135 and a discharge passage 130 through which oil is discharged.

The torque of the engine 100 is input to the sun gear 110 of the variable hydraulic pump through the input shaft 160, and the shaft one way clutch 155 is disposed on an exterior circumference of the input shaft 160 to have the input shaft 160 rotate only in one rotation direction. The ring gear one way clutch 150 is disposed on an exterior circumference of the ring gear 140 to have the ring gear 140 rotate only in the other rotation direction. The motor 145 rotates the ring gear 140 in the other rotation direction.

The torque that is input to the input shaft 160 is transmitted to the sun gear 110, the planetary gear 105, the ring gear 140, the carrier 115, and the output shaft 120 such that the hydraulic pump 135 pumps oil. When the engine 100 stops its operating, the motor 145 rotates the ring gear 140 to operate the hydraulic pump 135 in a minimum load, and when the engine 100 rotates the input shaft 160 slower than a predetermined velocity, the motor 145 operates the hydraulic pump 135 in a predetermined optimized load.

Referring to FIG. 2, the hydraulic pump 135 can be one of various types of pumps. For example, the hydraulic pump according to various embodiments of the present invention can use trochoid type internal gear.

FIG. 3 is a schematic diagram showing an operational method of a variable hydraulic pump that is disposed in a vehicle according to various embodiments of the present invention. Referring to FIG. 3, Ne denotes a rotation speed if the engine 100 or a rotation speed of the output shaft 120 or a rotation speed of the sun gear 110, Np denotes a rotation speed of the hydraulic pump 135 or the carrier 115, Nm denotes a rotation speed of the motor 145 or the ring gear 140, Zs denotes the number of the gear of the sun gear 110, and Zr denotes the number of the gear of the ring gear 140.

A rotation speed Np of the hydraulic pump 130 is determined by a lever principle, that is, Np can be determined by a rotation speed Ne of the engine 100, a rotation speed Nm of the motor 145, the number Zs the gear of the sun gear 110 and the number Zr of the gear of the ring gear 140. That is, if the rotation speed of the motor 145 is increased in a condition that the rotation speed of the engine 100 is fixed, the rotation speed of the hydraulic pump 135 is increased, and if the rotation speed of the engine 100 is increased in a condition that the rotation speed of the motor 145 is fixed, the rotation speed of the hydraulic pump 135 is increased.

FIG. 4 is a graph showing a compensation value that varies depending on oil temperature in a variable hydraulic pump according to various embodiments of the present invention. Referring to FIG. 4, a horizontal axis denotes oil temperature, and a vertical axis denotes alpha (a) value as a compensation value. The alpha value is used to control the target rotation speed of the hydraulic pump 135. Referring to FIG. 5, the usage method of the compensation value will be further described.

FIG. 5 is a flowchart showing a control method of a variable hydraulic pump that is disposed in a vehicle according to various embodiments of the present invention. Referring to FIG. 5, a control is started in S500, and it is determined whether the motor 145 is normal or not in S510. The method for determining whether the motor 145 is normal or not refers to disclosed arts and the detailed description thereof will be omitted in the present invention. If it is determined that the motor 145 is abnormal, a fail code is generated in S570, and the engine 100 is operated in a predetermined fail mode in S580. Here, the motor 145 is not operated, and the hydraulic pump 135 is operated by the engine 100.

It is determined whether a vehicle is in an idle stop (ISG) condition in S520 and S530. The idle stop condition (a condition that an engine is stopped in an idle condition) can be determined by a vehicle speed and a brake operating force. For example, the ISG condition is satisfied when a vehicle speed is less than or equal to a predetermined base value (ISG reference value) and a brake operating force is larger than or equal to a predetermined value (ISG reference value). If the vehicle is not in an idle stop condition, S550 is performed, and if the vehicle is in an idle stop condition, S540 is performed.

If it is determined that the engine 100 is stopped and Ne is zero (0) in S540, S590 is performed. The rotation speed (Nm) of the motor 145 is maintained at a predetermined value (N_isg) in S590. If it is determined that the rotation speed Ne of the engine 100 is not zero (0) in S540, it is determined whether oil temperature is larger than a reference value in S550. If it is determined that oil temperature is larger than a reference value, S560 is performed, and if it is determined that oil temperature is less than a reference value, S595 is performed.

A rotation speed (Nm) of the motor 145 is calculated by a controller through a formula −Zs/Zr*(Ne−(Np+α))−(Np+α) in S560. And, a rotation speed (Nm) of the motor 145 is calculated by a controller through a formula −Zs/Zr*(Ne−Np)−Np in S595.

FIGS. 6A, 6B, 6C and 6D are schematic diagrams showing operational conditions of a variable hydraulic pump of a vehicle according to various embodiments of the present invention.

FIG. 6A shows that an engine 100 is operated in an idle condition, wherein the rotation speed of the motor 145 is maintained to a relatively high state such that the rotation speed of the hydraulic pump 135 is maintained to a predetermined optimized value.

FIG. 6B shows that an engine 100 is operated in a low load condition, wherein the rotation speed of the motor 145 is maintained to a relatively middle state such that the rotation speed of the hydraulic pump 135 is maintained to a predetermined optimized value.

FIG. 6C shows that an engine 100 is operated in a high load condition, wherein the rotation speed of the motor 145 is maintained to a relatively low state or not operated such that the rotation speed of the hydraulic pump 135 is maintained to a predetermined optimized value.

FIG. 6D shows that an engine 100 is stopped to be operated, wherein the rotation speed of the motor 145 is maintained to an idle state such that the rotation speed of the hydraulic pump 135 is maintained to a predetermined optimized value.

In various embodiments of the present invention, the motor can be regarded as a stator of a general motor unit and the ring gear can be regarded as a rotor of the motor unit.

For convenience in explanation and accurate definition in the appended claims, the terms “interior” or “exterior”, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

What is claimed is:
 1. A vehicle having a variable hydraulic pump, comprising: a sun gear that receives a torque from a power source through an input shaft; a ring gear of which an interior circumference is with a distance from an exterior circumference of the sun gear; a planetary gear that is disposed between the interior circumference of the ring gear and the exterior circumference of the sun gear; a carrier that connects with an output shaft; a hydraulic pump that pumps oil through the output shaft that is connected to the carrier; and a motor that is disposed outside the ring gear to selectively rotate the ring gear.
 2. The vehicle having a variable hydraulic pump of claim 1, further comprising: a shaft one way clutch that has the input shaft rotate in one direction; and a ring gear one way clutch that has the ring gear rotate in the other direction.
 3. The vehicle having a variable hydraulic pump of claim 1, wherein the power source is an internal combustion engine or a motor.
 4. The vehicle having a variable hydraulic pump of claim 1, further comprising a controller that controls the motor depending on a rotation speed of the input shaft such that the hydraulic pump is controlled at a predetermined optimized speed.
 5. The vehicle having a variable hydraulic pump of claim 4, wherein the motor is operated at a predetermined rotation speed such that the hydraulic pump is operated at a minimum rotation speed in an idle stop condition.
 6. The vehicle having a variable hydraulic pump of claim 4, wherein a compensation value is applied to a target rotation speed of the hydraulic pump depending on a temperature of the oil, when the power source is operated. 